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Version: 1.3

CheerioCrawler

Provides a framework for the parallel crawling of web pages using plain HTTP requests and cheerio HTML parser. The URLs to crawl are fed either from a static list of URLs or from a dynamic queue of URLs enabling recursive crawling of websites.

Since CheerioCrawler uses raw HTTP requests to download web pages, it is very fast and efficient on data bandwidth. However, if the target website requires JavaScript to display the content, you might need to use PuppeteerCrawler or PlaywrightCrawler instead, because it loads the pages using full-featured headless Chrome browser.

CheerioCrawler downloads each URL using a plain HTTP request, parses the HTML content using Cheerio and then invokes the user-provided CheerioCrawlerOptions.handlePageFunction to extract page data using a jQuery-like interface to the parsed HTML DOM.

The source URLs are represented using Request objects that are fed from RequestList or RequestQueue instances provided by the CheerioCrawlerOptions.requestList or CheerioCrawlerOptions.requestQueue constructor options, respectively.

If both CheerioCrawlerOptions.requestList and CheerioCrawlerOptions.requestQueue are used, the instance first processes URLs from the RequestList and automatically enqueues all of them to RequestQueue before it starts their processing. This ensures that a single URL is not crawled multiple times.

The crawler finishes when there are no more Request objects to crawl.

CheerioCrawler downloads the web pages using the [utils.requestAsBrowser()](../api/utils#requestasbrowser) utility function. As opposed to the browser based crawlers that are automatically encoding the URLs, the [utils.requestAsBrowser()](../api/utils#requestasbrowser) function will not do so. We either need to manually encode the URLs via encodeURI() function, or set forceUrlEncoding: true in the requestAsBrowserOptions, which will automatically encode all the URLs before accessing them.

We can either use forceUrlEncoding or encode manually, but not both - it would result in double encoding and therefore lead to invalid URLs.

We can use the preNavigationHooks to adjust requestAsBrowserOptions:

preNavigationHooks: [
    (crawlingContext, requestAsBrowserOptions) => {
        requestAsBrowserOptions.forceUrlEncoding = true;
    }
]

By default, CheerioCrawler only processes web pages with the text/html and application/xhtml+xml MIME content types (as reported by the Content-Type HTTP header), and skips pages with other content types. If you want the crawler to process other content types, use the CheerioCrawlerOptions.additionalMimeTypes constructor option. Beware that the parsing behavior differs for HTML, XML, JSON and other types of content. For details, see CheerioCrawlerOptions.handlePageFunction.

New requests are only dispatched when there is enough free CPU and memory available, using the functionality provided by the AutoscaledPool class. All AutoscaledPool configuration options can be passed to the autoscaledPoolOptions parameter of the CheerioCrawler constructor. For user convenience, the minConcurrency and maxConcurrency AutoscaledPool options are available directly in the CheerioCrawler constructor.

Example usage:

// Prepare a list of URLs to crawl
const requestList = new Apify.RequestList({
    sources: [{ url: 'http://www.example.com/page-1' }, { url: 'http://www.example.com/page-2' }],
});
await requestList.initialize();

// Crawl the URLs
const crawler = new Apify.CheerioCrawler({
    requestList,
    handlePageFunction: async ({ request, response, body, contentType, $ }) => {
        const data = [];

        // Do some data extraction from the page with Cheerio.
        $('.some-collection').each((index, el) => {
            data.push({
                title: $(el)
                    .find('.some-title')
                    .text(),
            });
        });

        // Save the data to dataset.
        await Apify.pushData({
            url: request.url,
            html: body,
            data,
        });
    },
});

await crawler.run();

Properties​

stats​

Type: Statistics

Contains statistics about the current run.

requestList​

Type: RequestList

A reference to the underlying RequestList class that manages the crawler's Requests. Only available if used by the crawler.

requestQueue​

Type: RequestQueue

A reference to the underlying RequestQueue class that manages the crawler's Requests. Only available if used by the crawler.

sessionPool​

Type: SessionPool

A reference to the underlying SessionPool class that manages the crawler's Sessions. Only available if used by the crawler.

proxyConfiguration​

Type: ProxyConfiguration

A reference to the underlying ProxyConfiguration class that manages the crawler's proxies. Only available if used by the crawler.

autoscaledPool​

Type: AutoscaledPool

A reference to the underlying AutoscaledPool class that manages the concurrency of the crawler. Note that this property is only initialized after calling the CheerioCrawler.run() function. You can use it to change the concurrency settings on the fly, to pause the crawler by calling AutoscaledPool.pause() or to abort it by calling AutoscaledPool.abort().

new CheerioCrawler(options)​

Parameters:

cheerioCrawler.preNavigationHooks​

cheerioCrawler.postNavigationHooks​

cheerioCrawler.defaultRequestAsBrowserOptions​

cheerioCrawler.use(extension)​

EXPERIMENTAL Function for attaching CrawlerExtensions such as the Unblockers.

Parameters:

  • extension: CrawlerExtension - Crawler extension that overrides the crawler configuration.